From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46767) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gaLb4-0008Lk-IJ for qemu-devel@nongnu.org; Fri, 21 Dec 2018 09:16:15 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gaLb0-00007N-Bx for qemu-devel@nongnu.org; Fri, 21 Dec 2018 09:16:14 -0500 Received: from mx1.redhat.com ([209.132.183.28]:60714) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gaLb0-00006y-0D for qemu-devel@nongnu.org; Fri, 21 Dec 2018 09:16:10 -0500 From: Vitaly Kuznetsov Date: Fri, 21 Dec 2018 15:16:04 +0100 Message-Id: <20181221141604.16935-1-vkuznets@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Subject: [Qemu-devel] [PATCH] i386/kvm: add a comment explaining why .feat_names are commented out for Hyper-V feature bits List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eduardo Habkost Cc: qemu-devel@nongnu.org, Paolo Bonzini , Richard Henderson , Marcelo Tosatti , Roman Kagan Hyper-V .feat_names are, unlike hardware features, commented out and it i= s not obvious why we do that. Document the current status quo. Signed-off-by: Vitaly Kuznetsov --- target/i386/cpu.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/target/i386/cpu.c b/target/i386/cpu.c index 677a3bd5fb..18a486c5a0 100644 --- a/target/i386/cpu.c +++ b/target/i386/cpu.c @@ -929,6 +929,13 @@ static FeatureWordInfo feature_word_info[FEATURE_WOR= DS] =3D { */ .no_autoenable_flags =3D ~0U, }, + /* + * .feat_names are commented out for Hyper-V enlightenments because = we + * don't want to have two different ways for enabling them on QEMU c= ommand + * line. Some features (e.g. "hyperv_time", "hyperv_vapic", ...) req= uire + * enabling several feature bits simultaneously, exposing these bits + * individually may just confuse guests. + */ [FEAT_HYPERV_EAX] =3D { .type =3D CPUID_FEATURE_WORD, .feat_names =3D { --=20 2.19.2